only send a sample of the original data to the frontend (200 points)

src/main/java/eu/hbp/mip/controllers/ModelsApi.java

@@ -276,7 +276,7 @@ public class ModelsApi {
         datasetRepository.save(model.getDataset());
         modelRepository.save(model);
 
-        LOGGER.info("Model updated (also saved/updated model.config, model.query and model.dataset)");
+        LOGGER.info("Model updated (also saved/updated model.config and model.query)");
 
         return new ResponseEntity<>(HttpStatus.NO_CONTENT);
     }

src/main/java/eu/hbp/mip/utils/DataUtil.java

@@ -13,6 +13,8 @@ import java.util.Map;
 
 public class DataUtil {
 
+    private static final int NB_ROWS_SAMPLING = 200;
+
     private JdbcTemplate jdbcTemplate;
 
     public DataUtil(JdbcTemplate jdbcTemplate)
@@ -26,7 +28,10 @@ public class DataUtil {
 
         for (String var : vars) {
             JsonArray currentVarData = new JsonArray();
-            List<Map<String, Object>> queryResult = jdbcTemplate.queryForList("SELECT " + var + " FROM science.adni_merge");
+            int samplingPercentage = (int) countAdniRows()/NB_ROWS_SAMPLING;
+            List<Map<String, Object>> queryResult = jdbcTemplate.queryForList(
+                    "SELECT " + var + " FROM science.adni_merge " +
+                            "TABLESAMPLE SYSTEM ("+ samplingPercentage +") REPEATABLE ( 42 )");
             for (Map resultMap : queryResult)
             {
                 String strValue = String.valueOf(resultMap.get(var));
@@ -51,4 +56,11 @@ public class DataUtil {
         return count;
     }
 
+    public long countAdniRows()
+    {
+        long count = jdbcTemplate.queryForObject(
+                "SELECT COUNT(*) FROM science.adni_merge", Long.class);
+        return count;
+    }
+
 }